はてなブックマーク

Why are 2025/05/28 and 2025-05-28 different days in JavaScript? 2025-05-28 While setting up this site itself, I ran into the following oddity: console.log(new Date('2025/05/28').toDateString()); // Wed May 28 2025 console.log(new Date('2025-05-28').toDateString()); // Tue May 27 2025 // Bonus: (omit leading 0) console.log(new Date('2025-5-28').toDateString()); // Wed May 28 2025 You may get differ